For each system you create, you must have a separate set of talkgroups (which means you'd want a separate scanlist for those talkgroups).
If you create one system as a multisite system [and of course add the control channels for all the sites within that system that you want to monitor], that system will use one scanlist.
EX: I like to listen to the Ohio MARCS statewide system - five separate sites in particular.
1. I program one system and call it MARCS EAST.
2. In that system I enter the control channels for the five individual MARCS sites that I want to scan
3. I then add all the talkgroups I want to monitor to a scanlist (such as ScanList 2)
All of my talkgroups in ScanList 2 are set to be associated with the MARCS EAST system that i created above
I set the MARCS EAST system to "Multisite Stationary". That way, it scans every site for activity periodically.
I do NOT have it set to check all CCs in a single pass. The reason is that I have other scanlists (for another trunked system and a conventional scanlist) active at the same time. I don't want it to take 10 seconds (plus/minus) to scan ScanList 2 simply because I have the control channels for five sites plugged in. I want it to scan Scanlist 1, one active control channel in MARCS EAST in ScanList 2, then move on to ScanList 3. Then it come back around and repeats - and checks a different control channel (I assume) in Scanlist 2 each consecutive time.
If I DO set it to check all CC's in a single pass, then it is guaranteed to spend a large number of seconds on scanlist 2 during each complete scan of all my active scanlists, and I then miss too much traffic on my other scanlists.
You can have one system, programmed as multisite, using one set of talkgroups in a single ScanList.
Mike